Abstract
Abstract Tropospheric O 3 reduces growth and yield of many crop species, whereas CO 2 ameliorates the negative effects of O 3 . Thus, in a combined elevated CO 2 and O 3 atmosphere, seed yield is at least restored to that of charcoal‐filtered (CF) air at ambient CO 2 . The CO 2 ‐induced yield increase in CF air is highly variable, suggesting other potential resource limitations. To understand such variability in response, we tested that (1) competition for resources precludes some of the CO 2 enhancement on biomass and yield; and (2) O 3 reduces competition in elevated CO 2 . We grew rice ( Oryza sativa L.) at five densities in CF and O 3 ‐fumigated (+O3) air at ambient (A) and elevated [CO 2 ] (+CO2) in 1997 and 1998. O 3 reduced biomass by 25% and seed yield by 13–20% in A, but had little effect in +CO2. A competition model of biomass and yield response to density based on resource availability without competition showed that fewer resources were used for biomass in +O3 than in CF (average 53% vs. 70%) in A, while in +CO2 85% of resources were used for biomass regardless of O 3 suggesting greater depletion of resources. The enhanced biomass response to CO 2 with O 3 is consistent with a 22% greater CO 2 enhancement ratio [mass in +CO2 air/mass in A air; enhancement ratio (ER)] in +O3 than in CF air. For seed yield, few resources were used (average 17% and 25% for CF in 1997 and 1998, respectively), and ER was 13% greater in +O3. With competition the rate of change of individual plant biomass to density was not affected by +CO2 in CF air in 1997 but was increased 19% with more nutrients in 1998, indicating resource limitations with +CO2. The rate of change of individual plant yield to density was reduced with CO 2 in 1997 and unchanged in 1998 showing a different response to resource limitation for reproductive biomass. The resource use in +O3‐A suggested that increased density and soil fertility might compensate for pollutant damage. Although ambient [O 3 ] can modulate the response to elevated CO 2 , resource limitation precludes the CO 2 fertilization impact and both factors need consideration for better management and forecasts of future productivity.
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Claims 15
Claim · model-written summary
Ozone reduced rice biomass by 25% relative to charcoal-filtered air at ambient CO2.
- Taxon
- rice
Oryza sativae0 - Treatment
- O 3e1
- Outcome
- biomasse1
- Direction
- reducede1
- Value
- 25%e1
- Qualifier
- in Ae1
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“O 3 reduced biomass by 25% and seed yield by 13–20% in A, but had little effect in +CO2”
Claim · model-written summary
Ozone reduced rice seed yield by 13-20% relative to charcoal-filtered air at ambient CO2.
- Taxon
- riceOryza sativae0
- Treatment
- O 3e1
- Outcome
- seed yielde1
- Direction
- reducede1
- Value
- 13–20%e1
- Qualifier
- in Ae1
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“O 3 reduced biomass by 25% and seed yield by 13–20% in A, but had little effect in +CO2”
Claim · model-written summary
Ozone had little effect on rice biomass and seed yield under elevated CO2.
- Taxon
- riceOryza sativae0
- Treatment
- O 3e1
- Outcome
- had little effecte1
- Direction
- little effecte1
- Qualifier
- +CO2e1
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“O 3 reduced biomass by 25% and seed yield by 13–20% in A, but had little effect in +CO2”
Claim · model-written summary
In ambient CO2, a smaller share of resources was used for biomass under ozone than in charcoal-filtered air (average 53% vs. 70%).
- Taxon
- riceOryza sativae0
- Treatment
- +O3e1
- Outcome
- resources were used for biomasse1
- Direction
- fewere1
- Value
- 53% vs. 70%e1
- Qualifier
- in Ae1
- Comparator
- CFe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“fewer resources were used for biomass in +O3 than in CF (average 53% vs. 70%) in A”
Claim · model-written summary
Under elevated CO2, 85% of resources were used for biomass regardless of ozone.
- Taxon
- riceOryza sativae0
- Treatment
- +CO2e1
- Outcome
- resources were used for biomasse1
- Value
- 85%e1
- Qualifier
- regardless of O 3e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“in +CO2 85% of resources were used for biomass regardless of O 3”
Claim · model-written summary
The CO2 enhancement ratio of biomass was 22% greater in ozone-fumigated air than in charcoal-filtered air.
- Taxon
- riceOryza sativae0
- Treatment
- +O3e1
- Outcome
- CO 2 enhancement ratioe1
- Direction
- greatere1
- Value
- 22%e1
- Comparator
- CF aire1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“a 22% greater CO 2 enhancement ratio [mass in +CO2 air/mass in A air; enhancement ratio (ER)] in +O3 than in CF air”
Claim · model-written summary
For seed yield, few resources were used (average 17% for charcoal-filtered air in 1997 and 25% in 1998).
- Taxon
- riceOryza sativae0
- Outcome
- few resources were usede1
- Value
- 17% and 25%e1
- Qualifier
- for CF in 1997 and 1998e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“For seed yield, few resources were used (average 17% and 25% for CF in 1997 and 1998, respectively), and ER was 13% greater in +O3”
Claim · model-written summary
The seed yield CO2 enhancement ratio was 13% greater in ozone-fumigated air than in charcoal-filtered air.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“For seed yield, few resources were used (average 17% and 25% for CF in 1997 and 1998, respectively), and ER was 13% greater in +O3”
Claim · model-written summary
The rate of change of individual plant biomass with density was not affected by elevated CO2 in charcoal-filtered air in 1997.
- Taxon
- riceOryza sativae0
- Treatment
- +CO2e1
- Outcome
- rate of change of individual plant biomass to densitye1
- Direction
- not affectede1
- Qualifier
- in 1997e1
- Comparator
- CF aire1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“With competition the rate of change of individual plant biomass to density was not affected by +CO2 in CF air in 1997 but was increased 19% with more nutrients in 1998”
Claim · model-written summary
The rate of change of individual plant biomass with density was increased 19% by elevated CO2 in charcoal-filtered air in 1998, with more nutrients.
- Taxon
- riceOryza sativae0
- Treatment
- +CO2e1
- Outcome
- rate of change of individual plant biomass to densitye1
- Direction
- increasede1
- Value
- 19%e1
- Qualifier
- with more nutrients in 1998e1
- Comparator
- CF aire1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“With competition the rate of change of individual plant biomass to density was not affected by +CO2 in CF air in 1997 but was increased 19% with more nutrients in 1998”
Claim · model-written summary
The rate of change of individual plant yield with density was reduced by CO2 in 1997.
- Taxon
- riceOryza sativae0
- Treatment
- CO 2e1
- Outcome
- rate of change of individual plant yield to densitye1
- Direction
- reducede1
- Qualifier
- in 1997e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“The rate of change of individual plant yield to density was reduced with CO 2 in 1997 and unchanged in 1998”
Claim · model-written summary
The rate of change of individual plant yield with density was unchanged by CO2 in 1998.
- Taxon
- riceOryza sativae0
- Treatment
- CO 2e1
- Outcome
- rate of change of individual plant yield to densitye1
- Direction
- unchangede1
- Qualifier
- in 1998e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“The rate of change of individual plant yield to density was reduced with CO 2 in 1997 and unchanged in 1998”
Claim · model-written summary
Resource limitation is asserted to preclude the CO2 fertilization impact in rice.
- Taxon
- riceOryza sativae0
- Outcome
- CO 2 fertilization impacte1
- Qualifier
- resource limitation precludese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“resource limitation precludes the CO 2 fertilization impact”
Claim · model-written summary
Increased density and soil fertility might compensate for ozone (pollutant) damage in rice.
- Taxon
- riceOryza sativae0
- Outcome
- compensate for pollutant damagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“increased density and soil fertility might compensate for pollutant damage”
Claim · model-written summary
Both ozone and CO2 need consideration for better management and forecasts of future rice productivity.
- Taxon
- riceOryza sativae0
- Outcome
- better management and forecasts of future productivitye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We grew rice ( Oryza sativa L.) at five densities in CF”
e1“both factors need consideration for better management and forecasts of future productivity”
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